Field
The present disclosure relates generally to flowing electrolyte battery systems, and more particularly, to electrolyte distribution enhancement within high performance battery cells.
Background Information
Battery electrodes currently employed in flow batteries may have several performance and durability limitations. In zinc-bromine flowing electrolyte batteries, stacks share an aqueous zinc bromide electrolyte and each cell may have its own bi-polar electrode for deposit and dissolution of elemental zinc during charge and discharge cycles. In this type of battery, the electrolyte flow to a stack or specific cell(s) can be inhibited by poorly placed zinc deposits. Additionally, nucleation on electrodes can cause Zinc dendrite formation and branching between cells. As a result of the lowered zinc availability, the energy storage capacity of the neighboring stacks may be reduced. Another consequence is that the stack having the increased zinc accumulation may not fully deplete the zinc during discharge; eventually resulting in zinc accumulating on electrode sheets of the faulty stack to such an extent that may cause internal short circuiting between the cells of the stack which can potentially destroy the stack and possibly, the entire battery system. A further consequence is that the increased zinc accumulation can restrict the channels through which the electrolyte flows. As the electrolyte stream may act to cool the stack, the restricted flow may cause the stack to overheat and damage critical components. Therefore, zinc dendrites may reduce not only the performance of flow batteries but also the operating lifetime.
Additionally, flowing electrolyte batteries need a uniform electrolyte flow rate in each battery cell in order to supply chemicals evenly inside the battery cells. To achieve a uniform electrolyte flow rate through the cells, flowing electrolyte batteries define complex flow distribution zones. However, because electrolyte may have an oily, aqueous and gaseous multiphase nature, and because of structural constrain on the battery cells, uniform electrolyte flow rate is often not achieved.
For the foregoing reasons, there is a need for design and methods of flow channels which may provide good electrolyte distribution along the surface of electrode sheets, within electrochemical cells, in order to enhance flow battery conductivity and performance.